Safety switch for pumping units



Sept. 4, 1962 R. J. WALTER SAFETY SWITCH FOR PUMPING UNITS 2 Sheets-Sheet 1 Filed Feb. 24, 1960 IN VEN TOR. Raymond J. Walter p 4, 1962 R. J. WALTER 3,052,771

SAFETY SWITCH FOR PUMPING UNITS Filed Feb. 24, 1960 2 Sheets-Sheet 2 IN VEN TOR. Raymond J. Walter United States Patent 3,052,771 SAFETY SWITCH FOR PUMPING UNITS Raymond J. Walter, 75 S. Lincoln, Russell, Kans. Filed Feb. 24, 1960, Ser. No. 10,708 4 Claims. (Cl. 200-52) This invention relates to a safety switch for pumping units, and, more particularly, to a switch which can be mounted on the polish rod of a well pumping unit in such a manner that the switch will be closed if the pump rod in the well is broken, which in turn will short out the magneto of the power source and shut down the engine.

Devices exist in the prior art which are designed to prevent injury to the pumping unit upon breaks in the pump rod by providing some means for shorting out or stopping the engine of the pumping unit. These devices have proved to be unsuccessful or unsuitable for their intended job due to either the complicated and fragile structure of the devices, the expense of purchasing and maintaining them, or the difficulty in mounting them so that they will function properly.

In accordance with the present invention a new and improved safety switch for pumping units has been provided which overcomes the disadvantages of the prior art. The present device is lightweight in construction and can be easily mounted in a minimum length of time on the polish rod of the pumping unit. The device is so mounted relative to the hanger bar that any break in the pump rod is instantly sensed by the switch and transmitted to the magneto of the drive means of the pumping unit which is immediately shorted out. The present safety switch is relatively small in size when compared with the prior art devices which provides an additional savings in expense for shipping. The safety switch of the invention can be manufactured primarily from standard or stock items with a minimum amount of machining which further reduces the overall cost.

Accordingly, it is an object of this invention to provide a new and improved safety switch.

Another object of the invention is to provide a new safety switch which will instantaneously short out the magneto of the power unit of a well pumping engine if a pump rod breaks.

A still further object of the invention is to provide a new and improved safety switch which is economical to construct and inexpensive to ship.

A further object of the invention is to provide an improved safety switch which is easily mounted on a well pumping unit.

Various other objects, advantages and features of the invention will become apparent from the following description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a side elevation view of a common well pumping apparatus showing the invention in place there- FIGURE 2 is an enlarged isometric view of the improved safety switch of the invention.

FIGURE 3 is an elevation view of the safety switch of the invention.

FIGURE 4 is a cross sectional view taken along the line 44 of FIGURE 5.

FIGURE 5 is a top view of the safety switch mounted on the polish rod.

The following is a discussion and description of a preice ferred specific embodiment of the new safety switch of the invention, such being made with reference to the drawings whereon the same reference numerals are used to indicate the same or similar parts and/0r structure. It is to be understood that such discussion and description is not to unduly limit the scope of the invention.

The safety switch of the invention, shown in the drawings generally at 10, is designed primarily for use with well pumping units, usually called a pump jack. A typical well pumping unit is shown in FIGURE 1 and includes a gasoline engine 12 having a magneto 14 suitably mounted on a platform or base 16. The motor 12 drives a wheel 18 on which a pitman 20' is eccentrically mounted. The other end of pitman 20 is secured to a walking beam 22 which is pivotally mounted and supported by pillar bearings 23 on Samson post 24. The other end of the walking beam 22 has a horsehead 26 secured thereto. A hanger bar 28 is secured to the pump rod 30 a short distance beneath the horsehead 26. The cables for the hanger bar 28 are shown at '32. The safety switch 10 is mounted on the polish rod 34 above the hanger bar in a manner to be explained more fully hereinafter.

The safety switch of the invention, as best seen in FIGURES 2, 3, and 4, includes an elongated tubular housing or body 40 which is open at one end, and which is closed at the other end by a threaded plug or cap 42. The open end of the tubular housing or body 40 can be reduced in diameter as shown at 44. Housings of shapes other than the tubular one shown can, of course, be used.

An elongated rod 46 is slideably mounted in the housing or body 40 and extends through the open end of the housing. The end of the rod 46 within the housing 40 has an enlarged, metallic contact point or flange 48 rigidly secured to the end of the rod 46. The contact point 48 is preferably disc-shaped and secured to the end of the rod 46, however if desired it can be a projecting flange and secured to the rod intermediate the ends thereof. The other end of the rod 46 has a diagonally extending slot 50 cut through the center of the rod and in which a trigger 52 is pivotally secured by a pivot pin 53. The trigger is preferably bent intermediate its ends so that the portion of the trigger 52 or one side of the bend is longer than the portion on the other side of the bend, and it is pivotally secured on the rod in slot 50 in the bent portion.

An insulated terminal 54 passes through the side of the housing 40 and has a metallic contact point on plate 56 on the inside of the housing 40. Contact point 56 is preferably disc-shaped. The terminal 54 is secured to the side of the housing by a nut 58, or other suitable means. The terminal 54 is insulated from the housing 40 by pieces of insulating material 60 and 62 on the outside and inside of the housing 40* respectively.

A spiral spring 64 within the housing 40 urges the contact point or plate 48 on the rod 46 continually toward the contact point or plate 56 on the insulated terminal 54. The spiral spring 63 can be received within a suitable recess 64 in the plug or cap 42 to keep it centered on the plug. Other suitable means can, of course, be used to urge the contact points 48 and 56 into contact with each other. For example, a suitable resilient material such as rubber or synthetic foams of suitable dimensions and resiliency can be used.

As best seen in FIGURES 2 and 5, the safety switch I 10 of the invention can be secured to the polish rod 34 of a well pumping device by means of clamp sections 66 se- 3 cured together by a bolt 68 and a nut 70. Other means can, of course, be used to mount the safety switch in position.

In operation, the safety switch of the invention is secured to the polish rod 34 by the clamp means 66 in such a way that the helical spring 63 is compressed and the contact points 48 and 56 are not in engagement with each other. This is done by mounting the switch 10 above the hanger bar 28 with the short end of the trigger 52 in engagement with the hanger bar and with the spring 63 compressed. With the switch 10 in this position, an insulated wire 72 having a suitable conductor therein, is attached to the exposed end of the terminal 54 and the other end of the wire is attached to the magneto 14 of the power means. As long as the switch remains in this position with contact points 48 and 56 separated, the engine 12 will continue to operated. Should a break occur in the pump rod 30, the trigger 52 will be released from engagement with the hanger bar 28 as a result of recoil and the spiral spring 63 will immediately urge the contact points 48 and 56 into contact with each other. This shorts out the magneto 14 of the engine 12 and automatically shuts down the engine. As will be observed from FIGURES 2, 3, and 4, the trigger 52 is so constructed that one portion to one side of the bent portion of the trigger is smaller than the other portion. When mounting the device, the smaller portion is placed in engagement with the hanger bar. With the trigger in this position, only the slightest movement of the hanger bar will be necessary for the trigger 52 to pivot about the pin 53 which allows the contact points 48 and 56 to come into engagement with each other.

The housing 40, cap or plug 42, and rod 46 are preferably made of aluminum or aluminum alloys to reduce the shipping weight and cost, however, other metals and plastics can be used. Use of aluminum materials also eliminates the formation of crust on the moving parts which would impair the efficiency of the device.

While the invention has been described in connection with a preferred embodiment thereof, it will be understood that this deScription is intended to illustrate and not to limit the scope of the invention.

As will be evident to those skilled in the art, various modifications of the invention can be rnade, or followed in the light of this description and discussion without departing from the spirit of the disclosure or the scope of the claims.

-I claim:

1. A safety switch for well pumping units comprising, in combination, an elongated tubular housing open at one end, a threaded plug closing said housing at the other end, an elongated rod slidably mounted in said housing and projecting therefrom through said open end, an enlarged disc-shaped metallic contact point secured to the end of said rod within said tubular housing, an insulated terminal passing through the side of said housing and secured thereto, said terminal having a metallic contact point on the inside thereof connectable by an electric conductor to the magneto of a pumping motor, a helical spring compressed within said housing between said threaded plug and said contact point on said rod continually urging said contact point on said rod toward said contact point on said insulated terminal, a diagonally extending slot through the center of the end of said rod remote from said contact point, a trigger pivotally mounted on said rod within said diagonally extending slot, said trigger being bent intermediate its ends and pivotally joined to said rod in said bent portion thereof, an adjustable clamp engageable with said housing and operable to removably secure said safety switch to a polish rod of a well pumping unit so that said trigger engages the hanger bar thereof and said helical spring is compressed and said contact points on said rod and said terminal are out of engagement with each other, said device being constructed and adapted so that when a break occurs in the well pumping unit, said trigger on said rod will be released from engagement with the hanger bar and said helical spring will then urge said contact point of said rod into engagement with said contact point of said insulated terminal to thereby short out the magneto of the pumping motor.

2. In a safety switch for use with a well pumping unit having a gasoline engine with a magneto thereon, a walking beam, a pitman connecting one end of said walking beam to the gasoline engine, a horsehead on the other end of the walking beam, a polish rod depending from the horsehead, and a hanger bar secured to the jump rod, the improvement comprisng, in combination, an elongated tubular housing open at one end, a threaded plug closing said housing at the other end, an elongated rod slideably mounted in said housing and projecting therefrom through said open end, an enlarged disc-shaped metallic contact plate secured to the end of said rod within said tubular housing, an insulated terminal passing through the side of said housing and secured thereto, said terminal having a metallic contact plate on the inside thereof and having the outside connected to said magneto of said engine, a spiral spring compressed within said housing between said threaded plug and said contact plate on said rod continually urging said contact plate on said rod toward said contact plate on said insulated terminal, a diagonally extending slot through the center of the end of said rod projecting from said housing, a trigger pivotally mounted on said rod within said diagonally extending slot, said trigger being bent intermediate its ends and pivotally joined to said rod in said bent portion thereof, an adjustable clamp removably securing said safety switch to said polish rod so that said trigger engages said hanger bar and said spiral spring is compressed and said contact plates on said rod and said terminal are out of engagement with each other, said device being constructed and mounted so that when a break occurs in a polish rod said trigger on said rod will be released from engagement with said hanger bar and said spiral spring will then urge said contact plate on said rod into engagement with said contact plate of said insulated terminal to thereby short out said magneto to stop said engine.

3. A safety switch for well pumping units or the like comprising, in combination, a housing having an opening therein, an elongated rod slideably mounted in said housing and projecting therefrom through said opening therein, an electrical contact secured to the end of said rod within said housing, an electrical contact mounted inside said housing and connectable by an electrical conductor to the magneto of a pumping engine, means within said housing engaging said rod and biasing said electrical contact on said rod into engagement with said electrical contact mounted within said housing, a trigger freely pivotally. mounted on the end portion of said rod outside said housing to assume a vertical and horizontal position, said trigger having end portions at an angle to each other and mounted on said rod at the intersection of said end portions, said switch being constructed and adapted to be mounted on a well pumping unit or the like with one end portion of said trigger in engagement with apparatus in the well so that when a break occurs in the apparatus said trigger is released and said means within said housing engaging said rod urges said electrical contacts into engagement to thereby short out the magneto of the pumping engine.

4. Safety switch means for the power circuit of well pumping units and the like having pumping apparatus ex tending into a well comprising, in combination, a housing, rod means slideably mounted in said housing and having one end portion thereof projecting therefrom, an electrical contact connected to the other end portion of said rod means and positioned within said housing, an electrical contact mounted on said housing and engageable in oper- 5 ation by said first-named contact, means engaging said rod means and biasing said electrical contact thereon, trigger means freely pivotally mounted in an intermediate portion on said one end portion of said rod means to in operation assume a vertical and a horizontal position, said trigger means having one end portion normally engaging said pumping apparatus in operation to maintain said contacts in position to maintain said power circuit closed, and said trigger means constructed and mounted so that when a failure occurs in said pumping apparatus to break contact with said trigger means said trigger means is released and said means with said rod means biases said electrical contacts into position to maintain said power circuit open.

References Cited in the file of this patent UNITED STATES PATENTS 2,429,004 Wachsman Oct. 14, 1947 2,572,372 Montgomery Oct. 23, 1951 2,577,479 Owen et al. Dec. 4, 1951 2,671,162 Beline Mar. 2, 1954 2,711,462 Rouse June 21, 1955 2,928,912 Molnar Mar. 15, 1960 2,953,659 Edwards Sept. 20, 1960 

